A drill chuck can have a chuck body which can be driven by the drill spindle. The chuck jaws are guided in the chuck body, and they provide a retention means for the respective drilling tool. These jaws are adjustable by way of a control ring which can be rotated with respect to the chuck body, and which, furthermore, is guided so that it cannot be shifted or displaced in axial direction.
The apparatus can also include a lock sleeve which can be axially shifted with respect to the chuck body, and the position of the lock sleeve can be fixed in the direction of this axial movement or shifting movement. The lock sleeve secures the control ring and, accordingly, is spring biased in the displacement direction and against the control ring.
The drill chuck can have an axial passage which merges into the retainer for the drill tool. The impact action arising during the drilling, or during percussion drilling, is then directly transferable through this axial passage from the drill spindle to the drilling tool which is held with its respective end by the chuck jaws.
It is known, for example, from German Utility Model DE-GM No. 83 27 665, that an aperture in the drill chuck of this type can be formed by a slot in the wall of the lock sleeve, and an abutment head formed by the end of a pin of circular cross section extends radially into the aperture of the chuck body. When the pin contacts the lateral walls of the slot with its end, the lock sleeve is prevented from turning at the chuck body.
Furthermore, the lock sleeve is positioned so that it can be axially shifted between two positions, and it is provided at its end which is facing the control ring with teeth which are associated with opposite or complimentary teeth at the control ring.
When the lock sleeve is moved into the position against the control ring, the teeth of the lock sleeve engage in the opposite teeth and, accordingly, lock the control ring against undesired turning as, for example, from the impact action.
When the lock sleeve is moved away from the control ring, against the force of the spring, the teeth of the lock sleeve, however, are disengaged from the adjacent teeth of the control ring so that the control ring can be turned as desired.
However, manipulation is complicated when the lock sleeve is not engaged with the control ring.
To preclude rotation of the control ring is, however, particularly of importance with percussion tools because this will prevent that the drill chuck, during impact percussion operation, from working itself loose by itself. Another problem is excessive tensioning such that axial movement or shifting, which is per se desired, of the drilling tool in the retainer formed by the chuck jaws may be lost, and/or the chuck tightened to such an extent that it could be opened only with difficulty for replacing the drill.
The forces acting in the circumferential direction of the lock sleeve are correspondingly large, and these forces are taken up through the contact of the lateral walls of the slot at the pin end.
This abutment or contact is substantially linear so that a high specific wear of the respective material of construction occurs at the lateral wall of the slot and also at the end of the pin. Such excessive wear can easily lead to permanent deformations at the lateral wall of the slot and the end of the pin which, in the final analysis, can lead to permanent damage of the drill chuck.